PM Database Errors

[tqj]

I am having some problems with users getting a database error when sending PM's. It seems that the PM's go through but get the following error:

Database error in vBulletin 3.7.3:

Invalid SQL:

UPDATE user
SET pmtotal = pmtotal + 1, pmunread = pmunread + 1,
pmpopup =
CASE
WHEN userid IN(29) THEN 2
ELSE pmpopup
END

WHERE userid IN(29);

MySQL Error : MySQL server has gone away
Error Number : 2006
Request Date : Friday, November 7th 2008 @ 09:45:37 AM
Error Date : Friday, November 7th 2008 @ 09:46:10 AM
Script : http://www.theqjoint.com/forum/priva...insertpm&pmid=
Referrer : http://www.theqjoint.com/forum/private.php?do=newpm
IP Address : *******
Username : *******
Classname : vB_Database
MySQL Version :

Any help would be appreciated.